package filter;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.Map;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

/**
 * 通用编码解决方案
 *
 */
public class GenericEncodingFilter implements Filter {
    @Override
    public void destroy() {
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        // 转型为与协议相关对象
        HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        // 对request包装增强
        HttpServletRequest myrequest = new MyRequest(httpServletRequest);
        chain.doFilter(myrequest, response);
    }

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    }

}

// 自定义request对象
class MyRequest extends HttpServletRequestWrapper {

    private HttpServletRequest request;

    private boolean hasEncode;

    public MyRequest(HttpServletRequest request) {
        super(request);// super必须写
        this.request = request;
    }

    // 对需要增强方法 进行覆盖
    @Override
    public Map getParameterMap() {
        // 先获得请求方式
        String method = request.getMethod();
        if (method.equalsIgnoreCase("post")) {
            // post请求
            try {
                // 处理post乱码
                request.setCharacterEncoding("utf-8");
                return request.getParameterMap();
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }
        }
//        else if (method.equalsIgnoreCase("get")) {
//            // get请求
//            Map<String, String[]> parameterMap = request.getParameterMap();
//            if (!hasEncode) { // 确保get手动编码逻辑只运行一次
//                for (String parameterName : parameterMap.keySet()) {
//                    String[] values = parameterMap.get(parameterName);
//                    if (values != null) {
//                        for (int i = 0; i < values.length; i++) {
//                            try {
//                                // 处理get乱码
//                                values[i] = new String(values[i].getBytes("ISO-8859-1"), "utf-8");
//                            } catch (UnsupportedEncodingException e) {
//                                e.printStackTrace();
//                            }
//                        }
//                    }
//                }
//                hasEncode = true;
//            }
//            return parameterMap;
//        }
        return super.getParameterMap();
    }

    @Override
    public String getParameter(String name) {
        Map<String, String[]> parameterMap = getParameterMap();
        String[] values = parameterMap.get(name);
        if (values == null) {
            return null;
        }
        return values[0]; // 取回参数的第一个值
    }

    @Override
    public String[] getParameterValues(String name) {
        Map<String, String[]> parameterMap = getParameterMap();
        String[] values = parameterMap.get(name);
        return values;
    }

}

